High above Washington National Cathedral, in a brick-wall chamber reachable by a tiny elevator, a group of 10 men and women stood expressionless Saturday, each holding on to the end of a rope. In their minds, they began to count.

“Look to,” Beth Sinclair, 55, said to the group, pulling down on the rope. “Treble’s going . . . she’s gone.”

Thirty feet above, some of the heaviest bells in North America began to ring, sending a crescendo of notes across the nation’s capital, each ring separated by about a 25th of a second.

Gathered in the tower were a group of musicians that are often heard but rarely seen. They are bell ringers, the humans behind the sounds associated with milestones of great joy or sorrow, with weddings and funerals and presidential inaugurations.

But on Saturday, they gathered for something else entirely — the second annual Trinity Shield Striking Competition, a weekend of competition among some of the country’s best bell ringers.

Eight teams from across the country took turns performing the centuries-old tradition of change-ringing, an art that requires a band of ringers to rhythmically control a set of tuned bells, playing patterns of notes called “methods.”

Mark Regan, ringing master at Worcester Cathedral in England, takes a rope as teams practice prior to a change-ringing competition at the Washington National Cathedral on Saturday October 20, 2018 in Washington. (Keith Lane/For The Washington Post)

Each team, consisting of either six or eight bell ringers, was judged by one of the most accomplished change-ringers in the United Kingdom, Mark Regan, who flew in Thursday from Worcester, England, for the event.

The competition was intended to be held at New York’s Trinity Church Wall Street. But because that church is undergoing construction, the Washington Ringing Society offered to host the event in Washington National Cathedral, home to a set of 10 bells as wide as 55 inches and as heavy as 3,588 pounds.

Washington National Cathedral is one of about 50 change-ringing bell towers in North America, which also include the Old Post Office Tower — now incorporated into the Trump International Hotel — in downtown Washington.

Change-ringing, which originated in the 17th century in England, is at once musical, mathematical and physical.

The Washington National Cathedral’s bells are balanced upside-down as to allow them to be pulled all the way round by a rope. (Keith Lane/For The Washington Post)

It requires careful counting, focus and “unconscious teamwork,” Regan said. If one person makes an error, the whole sequence is ruined. While each performance Saturday lasted only a few minutes, change-ringers can perform for up to three hours at a time; Regan once rang for 14 hours straight.

“You’re controlling a fast-moving piece of metal 30 feet above your head to split-second accuracy, controlling a piece of rope that disappears through a hole in the ceiling,” Regan said. “It’s pretty loopy.”

Three teams at Saturday’s competition hailed from the Washington Ringing Society, the reigning champs of last year’s contest. Its members voluntarily ring bells at both the Cathedral and the Old Post Office. The group has rung in remembrance of 9/11, for President Obama’s inauguration, for the Supreme Court decision effectively legalizing same-sex marriage, and for the funerals of President Ronald Reagan and Sen. John McCain.

“When the bells are ringing, I think that people often have no idea that it’s humans doing it,” said Sinclair, a 55-year-old Bethesda resident who has been ringing for 40 years, since she was a student at National Cathedral High School next door.

Despite their association with the Cathedral, many of the group’s members, including Sinclair, are not religious. “I don’t ever go to church,” she said. “So it’s very ironic that I spend this much time at churches.”

For Sinclair, like many of her fellow ringers, change-ringing is a mental challenge, like solving a puzzle.

“When it’s really beautiful, it’s just like light on water,” she said. “It’s kind of transformative. We don’t hit that that often, but you are chasing it all the time.”

As the teams performed Saturday, several stories above the Cathedral, their judge sat alone in a dimly lit room in the National Cathedral School, listening to the bells from afar through open windows.

“That’s the signal,” Regan said, hearing the last bell of one team’s practice set. He set a timer on his phone. “I’ve got to think now.”

As the six bells chimed one after the other in careful sequence, Regan held his forehead in his hand, leaning against a long wooden table. He scrawled out notes on a sheet of paper, keeping a tally of the number of times when the sequence was uneven. He counted in his head, imagining himself in that circle, performing an art he has known since he was a teenage boy growing up in England.

“They sounded nervous,” he said. “They had a few moments that could have gone badly, but they were determined. You could sense that.”

After four hours of competition and the notes from the last bells had dissipated into the late afternoon air, Regan studied his notes and chose a winner: The Washington Ringing Society would claim the title, for the second year in a row.